Follicular lymphoma

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What is Follicular lymphoma?

Follicular Lymphoma is cancer of the lymphatic system. There are two broad categories of lymphoma: Hodgkin's lymphoma and non-Hodgkin's lymphoma. Follicular lymphoma is a type of non-Hodgkin's lymphoma.

Lymphatic system is an important part of our immune system that helps fight infection. It is composed of various organs e.g. lymph nodes, thymus, spleen and bone marrow. These are connected by a network of tiny lymphatic vessels.

Lymph is a colourless fluid that circulates in the lymphatic system. It contains lymphocytes, which are white blood cells that fight infection. There are 2 types of lymphocytes: B cells and T cells. Follicular lymphoma is a cancer of B cells. It is called follicular lymphoma because the malignant cells usually grow in a circular or follicular pattern in the lymph nodes.

Who gets Follicular lymphoma?

Follicular lymphoma is one of the commenest types of lymphoma in Western countries. Follicular lymphoma accounts for 20-30% of all lymphomas. Follicular lymphoma is the most common type of slow-growing or indolent non-Hodgkin's lymphoma.

Variations in racial incidence are found. The incidence of follicular lymphomas is low in China and Japan. People of Jewish ancestry have a higher incidence.

The incidence of follicular lymphomas increases with age. Most patients are around 60 years old when the disease is diagnosed. Follicular lymphomas are extremely rare in children. The ratio of male to female affected is about 2:3.

Predisposing Factors

Age: Middle-aged and elderly people.

Gender: Slightly more common in female.

Ethnicity: Less common in the Asian and African American populations.

There are changes in the gene involving transfer of part of the gene to a different location, called t(14;18) gene translocation, which results in overexpression of a protein BCL-2.

Progression

When follicular lymphoma is diagnosed, it is mostly already at an advanced stage.

Follicular lymphoma patients usually come with widespread enlargement of the lymph nodes in multiple parts of the body.

World Health Organization (WHO) classifies follicular lymphoma into three different grades, according to the number of large cells they contain:

Grade I, or small-cleaved cell type: a person has fewer than five large cells per high power field under the microscope.

Grade II, or mixed small-cleaved and large cell type: a person has between 6 and 15 large cells per high power field under the microscope.

Grade III, or large cell type: a person has more than 15 large cells per high power field.

Grade I is the most common type. Grades I and II are generally considered to be indolent, or slow-growing. Grade III follicular lymphoma is more fast-growing, and requires aggressive treatment.

Follicular lymphoma can become more aggressive over many years, and the follicular pattern may change from a lower percentage of large cells to primarily large cells.

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